#!/usr/bin/env bash
# diagnose_melonds.sh - Automated diagnostics for melonDS via GDB
set -euo pipefail

ELF_FILE="${1:-snakePlus.elf}"

if [ ! -f "$ELF_FILE" ]; then
  if [ -f "build-debug/snakePlus.elf" ]; then
    ELF_FILE="build-debug/snakePlus.elf"
  elif [ -f "build/snakePlus.elf" ]; then
    ELF_FILE="build/snakePlus.elf"
  else
    echo "[-] Error: ELF file not found: $ELF_FILE"
    exit 1
  fi
fi

# Locate arm-none-eabi-gdb
GDB_BIN="arm-none-eabi-gdb"
if [ -n "${DEVKITPRO:-}" ] && [ -x "${DEVKITPRO}/devkitARM/bin/arm-none-eabi-gdb" ]; then
  GDB_BIN="${DEVKITPRO}/devkitARM/bin/arm-none-eabi-gdb"
elif ! command -v "$GDB_BIN" &>/dev/null; then
  echo "[-] Error: arm-none-eabi-gdb not found on PATH or DEVKITPRO."
  exit 1
fi

echo "[*] Connecting to melonDS on localhost:3333 using $ELF_FILE..."

# Run GDB in batch mode to gather CPU state
GDB_OUTPUT=$("$GDB_BIN" "$ELF_FILE" --batch \
  -ex "set confirm off" \
  -ex "set pagination off" \
  -ex "target remote localhost:3333" \
  -ex "info registers" \
  -ex "x/x 0x02fffd98" \
  -ex "x/x 0x02fffd90" \
  -ex "detach" \
  -ex "quit" 2>&1 || true)

if echo "$GDB_OUTPUT" | grep -q "Connection refused"; then
  echo "[-] Could not connect to localhost:3333. Ensure melonDS is running with GDB enabled."
  exit 1
fi

echo "=== Registers ==="
echo "$GDB_OUTPUT" | grep -E "^(r0|r4|r8|r12|sp|lr|pc|cpsr)" || true

PC=$(echo "$GDB_OUTPUT" | awk '/^pc/ {print $2}')
SP=$(echo "$GDB_OUTPUT" | awk '/^sp/ {print $2}')

echo ""
echo "=== CPU Analysis ==="
echo "Current PC: $PC"
echo "Current SP: $SP"

if [ "$PC" = "0x1ff8594" ] || [ "$PC" = "0x01ff8594" ]; then
  echo "[!] CPU is trapped in __excpt_entry (Fatal Exception / Data Abort / Prefetch Abort)!"
  FAULT_ADDR=$(echo "$GDB_OUTPUT" | awk '/0x2fffd98:/ {print $2}')
  FAULT_SPSR=$(echo "$GDB_OUTPUT" | awk '/0x2fffd90:/ {print $2}')
  echo "    Faulted Instruction Address (lr_abt - 8): $FAULT_ADDR"
  echo "    Faulted SPSR: $FAULT_SPSR"

  if [ -n "$FAULT_ADDR" ] && [ "$FAULT_ADDR" != "0x0" ]; then
    echo "=== Source Location ==="
    "$GDB_BIN" "$ELF_FILE" --batch \
      -ex "info line *$FAULT_ADDR" \
      -ex "quit" 2>&1 | grep -v "^(gdb)" || true
  fi
elif [ "$PC" = "0x1ff84ec" ] || [ "$PC" = "0x01ff84ec" ]; then
  echo "[+] CPU is sleeping in armWaitForIrq (Normal running state waiting for VBlank/Timer IRQ)."
else
  echo "[*] CPU is running user code at $PC."
  "$GDB_BIN" "$ELF_FILE" --batch \
    -ex "info line *$PC" \
    -ex "quit" 2>&1 | grep -v "^(gdb)" || true
fi